Accounts of mall mayhem on Black Friday — the day after Thanksgiving in the U.S., when merchants offer deep discounts on everything from skis to sandwich grills — have become part of retail lore. And although such incidents are rare, midnight store openings, across-the-parking-lot lineups and unbelievable deals have become as iconic of American Thanksgiving as pumpkin pie and pilgrim outfits.

Each year, more Canadians join the Black Friday fray — the moniker reflects the fact that it puts retailers “in the black” for the year. Statistics Canada says 4.2 million Canadians travelled to the U.S. last November, presumably to shop. This year, stores in Canada, including The Bay, amazon.ca, Gap and Toys R Us are all trumpeting Black Friday specials.

Still, Sally Ritchie, vice president of communications and marketing for the Retail Council of Canada says Canadians aren’t entranced with cross-border door-busting. “Our polling data shows that only six per cent of people in British Columbia and five per cent of Ontarians plan to travel to the U.S. for Black Friday,” Ritchie says; 94 per cent of Canadians will be staying put.

So for most Canadians, it seems, the question isn’t, “Where does the line start?,” but, “What the heck?”

Well, obviously, there are the deals. “It can be thrilling to get a key item for a really good price,” says Sarah Kutulakos, an American now living in Canada. “And there’s the social aspect, the ritual. You have Thanksgiving dinner with family and friends, then you all get up early on Friday to go shopping.” (Note: Kutulakos admits she doesn’t go in for lining up herself.)

But more subtle psychology may be at work as well. Aparna Labroo, a consumer psychologist and the Patricia C. Ellison Professor of Marketing at the Rotman School of Management, University of Toronto, points out that people want things more when they appear scarce.

Deep discounts, offering those savings for a limited time and making only a few of those products available (to, say, the first 100 customers) are all ways retailers “manipulate scarcity cues” — in other words, motivate consumers.

Enough to pitch a tent in an overnight lineup? Maybe. “People actually infer value (of a product) from the effort they put into getting that product,” says Labroo.

In other words, having to line up is — for some shoppers — not only not a deterrent, it’s proof that what they want is worth lining up for. “The many people present, all waiting, can heighten the sense of scarcity.”